1. Field of the Invention
The present invention relates to an evaporating fuel processing apparatus and method for processing evaporating fuel generated in a fuel tank and discharging it towards an air intake system of the internal combustion engine, and in particular, to an apparatus having a function of determining presence or absence of leakage of evaporating fuel in an evaporating-fuel-discharge suppression system which is provided between the fuel tank and the air intake system.
2. Description of the Related Art
A typical conventional apparatus for processing evaporating fuel comprises a fuel tank, a canister for absorbing evaporating fuel generated in the fuel tank, a charge passage for joining the canister and the fuel tank, a purge passage for connecting the canister and an engine air intake system, and the like. Japanese Unexamined Patent Application, First Publication, No. Hei 7-12016 discloses a method of determining presence or absence of leakage of such an evaporating fuel processing apparatus.
In the disclosed method, in the general operation mode of the engine, if a detected internal pressure in the tank is negative with respect to the atmospheric pressure by a predetermined value or more, then it is determined that no leakage of evaporating fuel has occurred from the evaporating fuel processing apparatus and the purge operation is being executed under normal conditions. If it is not determined that the present state is normal, for example, when the internal pressure of the fuel tank stays at approximately the atmospheric pressure for a predetermined time, then it is determined that leakage may be occurring, and a leakage diagnosis process is executed. In this process, a discharge suppression system including the evaporating fuel processing apparatus is made to have a negative-pressure state, and the presence or absence of leakage is determined with reference to the ability of maintaining the negative pressure.
On the other hand, Japanese Unexamined Patent Application, First Publication, No. Hei 9-317572 discloses an evaporating fuel processing apparatus having a bypass valve for bypassing a pressure regulating valve provided in a charge passage for joining a fuel tank and a canister, and the evaporating fuel processing apparatus determines presence or absence of leakage in both of (i) the fuel tank side from the bypass valve to the fuel tank, and (ii) the canister side from the bypass valve to the canister.
In the determination of the presence or absence of leakage in the fuel tank side, the bypass valve is opened immediately after the internal combustion engine is started, so as to increase the pressure in the fuel tank towards the atmospheric pressure, and if the variation of the pressure in the fuel tank is larger than a predetermined value, then it is determined that no leakage of the fuel tank is found and the operation thereof is normal. That is, if leakage occurs in the fuel tank, the pressure in the fuel tank before the start of the internal combustion engine is approximately equal to the atmospheric pressure, and thus the variation of the pressure in the fuel tank is small.
In the above-explained conventional evaporating fuel processing apparatuses, when the internal combustion engine is started, various initial processes are performed, for example, (i) the pressure value in the fuel tank at the starting time is stored, (ii) the timer value of a subtraction timer, referred to in the process of determining the presence or absence of leakage, is set to a predetermined initial value, and (iii) various parameters such as the elapsed time from the starting time of the internal combustion engine and the total value of the fuel consumption are initialized.
If a vehicle is driven in an idle driving state, an xe2x80x9cidle stopxe2x80x9d operation may be executed, in which the internal combustion engine is stopped and any unnecessary idle driving operation is prohibited so as to reduce fuel consumption. If the idle stop and restart of the internal combustion engine are alternately performed, then the parameters referred to in the process of determining the presence or absence of leakage are initialized every time the internal combustion engine is restarted. However, some parameters need their initial values provided when the internal combustion engine is first started (that is, when the internal combustion engine is cold). Therefore, the presence or absence of leakage may not be determined correctly.
In consideration of the above circumstances, an objective of the present invention is to provide an evaporating fuel processing apparatus and method of an internal combustion engine, which can reliably determine the presence or absence of leakage even if stopping and restarting operations of the internal combustion engine are alternately repeated after the internal combustion engine is initially started.
Therefore, the present invention provides an evaporating fuel processing apparatus of an internal combustion engine, comprising:
a fuel tank;
an evaporating fuel discharge suppression system for processing evaporating fuel generated in the fuel tank;
a leakage detecting section for detecting leakage in the evaporating fuel processing apparatus by referring to one or more parameters;
a stop condition determining section for determining whether a predetermined condition for stopping the internal combustion engine is satisfied;
a stop section for stopping the internal combustion engine when the stop condition determining section determines that the predetermined condition is satisfied;
a restart section for restarting the internal combustion engine after the internal combustion engine is stopped by the stop section;
a storage section for storing the one or more parameters referred to by the leakage detecting section; and
an initializing section for initializing the one or more parameters when an ignition switch for starting the internal combustion engine is switched on.
The processes of steps S210 to S223, S306 to S311, and S404 to S421 explained later disclose an example of the detection performed by the leakage detecting section. The leakage detecting section, stop condition determining section, stop section, restart section, storage section, and initializing section can be realized by using, for example, an ECU 13 explained below. The processes of steps S206 to S208, S303, and S403 explained below disclose an example of the initialization process executed by the initializing section.
According to the above structure, the initializing section initializes the one or more parameters only when an ignition switch for starting the internal combustion engine is switched on. Therefore, after the internal combustion engine is initially started, even if the operations of (temporarily) stopping and restarting the internal combustion engine are repeated due to the idle stop or the like, it is possible to prevent the above parameters from being initialized for each restart. Accordingly, the presence or absence of leakage of the evaporating fuel processing apparatus of the internal combustion engine can be reliably performed.
The evaporating fuel processing apparatus may further comprise a pressure detecting section for detecting the internal pressure of the fuel tank as a parameter referred to by the leakage detecting section and stored by the storage section.
On the other hand, the evaporating fuel processing apparatus may further comprise a timer for measuring the elapsed time from the starting time of the internal combustion engine as a parameter referred to by the leakage detecting section and stored by the storage section.
Typically, the evaporating fuel processing apparatus is mounted in a vehicle, and the predetermined condition may be that the speed of the vehicle is below a predetermined value, and the shift position of the vehicle is in a neutral or parking position.
The present invention also provides an evaporating fuel processing method of an internal combustion engine, applied to an evaporating fuel processing apparatus comprising a fuel tank, and an evaporating fuel discharge suppression system for processing evaporating fuel generated in the fuel tank, the method comprising:
a leakage detecting step for detecting leakage in the evaporating fuel processing apparatus by referring to one or more parameters;
a stop condition determining step for determining whether a predetermined condition for stopping the internal combustion engine is satisfied;
an engine stopping step for stopping the internal combustion engine when it is determined in the stop condition determining step that the predetermined condition is satisfied;
a restarting step for restarting the internal combustion engine after the internal combustion engine is stopped in the engine stopping step;
a storage step for storing the one or more parameters referred to by the leakage detecting step in a storage device; and
an initializing step for initializing the one or more parameters stored in the storage device when an ignition switch for starting the internal combustion engine is switched on.
The present invention also provides a computer readable storage medium storing a program for making a computer execute an evaporating fuel processing operation of an internal combustion engine, applied to an evaporating fuel processing apparatus which comprises a fuel tank, and an evaporating fuel discharge suppression system for processing evaporating fuel generated in the fuel tank, the operation comprising:
a leakage detecting step for detecting leakage in the evaporating fuel processing apparatus by referring to one or more parameters;
a stop condition determining step for determining whether a predetermined condition for stopping the internal combustion engine is satisfied;
an engine stopping step for stopping the internal combustion engine when it is determined in the stop condition determining step that the predetermined condition is satisfied;
a restarting step for restarting the internal combustion engine after the internal combustion engine is stopped in the engine stopping step;
a storage step for storing the one or more parameters referred to by the leakage detecting step in a storage device; and
an initializing step for initializing the one or more parameters stored in the storage device when an ignition switch for starting the internal combustion engine is switched on.